Have a shower!
No, this is not a joke!! Have a shower, and hold your arm(s) in the second position. If you do not have large enough space, you can do it with the first position, but it can be a little harder. Trickle water down your arm.
If your arm(s) is held in just the right position, you will feel a drop of water trickle all the way down the under side of your arm without dropping till the end of your little finger. If your arms are help with inside the elbow and palm facing forward, with shoulders nicely pulled back and relaxed, this really will happen!
There is a lovely clip of Rudolf Nureyev in class, and while he is doing some barre work, the camera puns along his arm which is held in second position. As the camera moves along his arms from his shoulder to his hand, a trickle of sweat can be seem moving down his arm and drips right from the end of his little finger!
Many of my dancers tried it and reported back that it works!